Hey all,
been lurking for a bit and just became a member. I got a '82 720 KC that just passed the 240K mark. Got it about a year ago and have slowly been fixing things up on it.
So the question I need help with is with that thick oily smoke on startup and harder accelerations. I have no external oil leaks except a tiny bit from the pan seal, but it still eats about a quart a month. I've been told that it's probably a piston seal or four, or maybe the valve guides, that are leaking. I don't know too much about the internal engine parts, been too cautious to open that up.
So, is it true, about the seals and/or guides? Or are there other possible causes? If it's the seals, does that mean a engine rebuild?
Thanks for all the other good info,
Joshua
Reducing oil smoke
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As a GENERAL rule....for knackered engines (smoke may be caused by other reasons) BLUE engine oil smoke on power (acceleration, uphills etc)= worn piston rings/bores.
BLUE engine oil smoke on deceleration (lifting of foot,engine breaking going down hill etc)= worn valve guides/seals.
On start up it could be valve guides/seals allowing oil past whilst standing.
There is no reason why both can't be knackered.
Are you using the correct oil??? If engine has breathing system other than open road draft tube is that blocked??
BLUE engine oil smoke on deceleration (lifting of foot,engine breaking going down hill etc)= worn valve guides/seals.
On start up it could be valve guides/seals allowing oil past whilst standing.
There is no reason why both can't be knackered.
Are you using the correct oil??? If engine has breathing system other than open road draft tube is that blocked??
turbo it
(sd33t home turbo set up if anyone is interested..)
(sd33t home turbo set up if anyone is interested..)
- philip
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- Location: Southern California, USA
Re: Reducing oil smoke
First ... please tell who/what you are. ThanksViridiansky wrote:Hey all, I've been lurking for a bit and just became a member. I got a '82 720 KC that just passed the 240K mark.
-snip-
So the question I need help with is with that thick oily smoke on startup and harder accelerations. I have no external oil leaks except a tiny bit from the pan seal, but it still eats about a quart a month.
-snip-
So, is it true, about the seals and/or guides? Or are there other possible causes?
In the SD22 engines you'll notice an oil blowby pipe (Road Draft tube) exiting on the low left side of the engine block which ... will NORMALLY lose oil that works back round the rear of the engine pan. So even if rings, stem seals, etc were -perfect-(...this can NEVER be...) the engine crankcase would still lose a lot total oil. Notice your clean driveway! Notice the SD25 is different (in several way).
"...thick oily smoke on startup and harder accelerations." What you see on a start-up puff is normal for old type diesels. Then, "smoke" seeing during accelation is not likely to do with oil. Rather ... the black smoke (exhaustion) results from too much fuel (carbon "soot"). Whole different discussion.
-Philip
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
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Re: Reducing oil smoke
Thanks for the info on the blowby pipe. I'll take a look at it. and the hint about seals vs. guides.
thanks again.
Has this discussion happened yet. Where can I find it?philip wrote:Rather ... the black smoke (exhaustion) results from too much fuel (carbon "soot"). Whole different discussion.
thanks again.
Joshua
'82 720 KC with SD22
'82 720 KC with SD22
- philip
- Deceased
- Posts: 1494
- Joined: 18 years ago
- Location: Southern California, USA
Re: Reducing oil smoke
There are several soot, oil, exhaustion, emission discussions ... already in these forums. Have you "happened" yet?Viridiansky wrote:Has this discussion happened yet. Where can I find it?philip wrote:Rather ... the black smoke (exhaustion) results from too much fuel (carbon "soot"). Whole different discussion.
thanks again.
Last edited by philip 17 years ago, edited 1 time in total.
-Philip
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
- asavage
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Re: Reducing oil smoke
Reminds me of author Dean Koontz's "becoming" phrase that he uses in a couple of his novels.philip wrote:Have you "happened" yet?
What did you mean by "happened"?
Regards,
Al S.
1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
Al S.
1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
- philip
- Deceased
- Posts: 1494
- Joined: 18 years ago
- Location: Southern California, USA
Re: Reducing oil smoke
RE: "Has this discussion happened yet. Where can I find it?"asavage wrote:Reminds me of author Dean Koontz's "becoming" phrase that he uses in a couple of his novels.philip wrote:Have you "happened" yet?
What did you mean by "happened"?
I asked "Viridiansky" to find forums cluing smoke titles. Three pages of forums exist.
-Philip
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
"Im slow and I'm ahead of you"
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